Besides just a fan, there is not. The reason is that the heat removed from the room has to go somewhere. Otherwise you are at best just running a dehumidifier. The venting on a portable air conditioner both removes heat from the room, evaporates the moisture and expels it outside.

If you don't vent the portable A/C, you will actually have a net gain of heat because you will have used electrical energy, which creates heat, to transfer heat from one side of the unit to the other as cool air! Unfortunately, both sides of the unit are in the same airspace.